In the emerging 6G, integrated satellite-terrestrial networks can provide a scenario of Internet access with expanded coverage and seamless connectivity[1]}, [2]}. The use cases of integrated satellite-terrestrial networks have attracted a lot of attention in applications such as Internet-of-things (IoT), vehicle-to-everything (V2X), holographic communications, etc[3]}, [4]}, [5]}, [6]}. With the increasing number of connective devices and abundant service requirements, the spectrum resource of space information networks is increasingly scarce[7]}. To address this issue, the spectrum sharing within satellite-terrestrial networks and frequency reuse among multiple beams of satellite are widely adopted to improve the spectrum utilization[8]}. However, the co-channel/inter-beam interference caused by the spectrum sharing and frequency reuse degrades the overall communication performance[9]}, [10]}, [11]}, and the security vulnerability is opportunistic to penetrate crossing satellite and terrestrial networks[12]}, [13]}. Particularly, due to the openness of wireless channels and the broad broadcasting coverage, the integrated satellite-terrestrial communications are vulnerable to eavesdropping threats and the very large and complex geographical areas give harbour to attackers and eavesdroppers (Eves), which results in serious security issues.
